I live in the south bay, CA and just got my first two starter bonsai trees last summer (shimpaku juniper and dawn redwood - both live outside). After reading blogs and watching a bunch of videos, I finally got the courage to re-pot this last weekend since it’s already getting warm here (does that shorten winter dormancy?).

I ran into a snag with the juniper that I could use some help with. Once I removed the top soil and began raking out the roots, I discovered multiple HUGE roots (that were pretty woody) that all seemed to curve backwards and around to the point where I couldn’t even determine where each one started and ended. I was torn on what to do for multiple reasons:

I read that you should not remove all the soil on junipers (something about good bacteria?), so I was afraid to keep digging

I know you should remove any larger/tap roots b/c they take up too much of the tree’s resources, but…

I think I saw that unlike other trees, certain roots on junipers feed certain parts of the tree, so I didn’t want to just blindly cut the big roots off and risk killing parts of the tree

I actually wanted to keep a couple of them as part of the root flare

To be on the safe side (in the interest of time and not exposing the roots too long), I ended up just removing a couple medium sized roots, trimming the long/thin ones, and re-potting it with the larger roots in tact in a 1/3 akadama, lava, and pumice mix. Any tips and recommendations would be GREATLY appreciated.

Here are pics of the roots in question and after re-potting. *I think my tap water is making the trunk turn salty/white and am in the process of fixing that (it also gets misted regularly).

It looks like you did a good job. The only trick I know of in this case is to bare root about 50% of the rootball to get a better idea of what’s going on, at least on one side of the tree. I then do the same thing on the other side about 2 years later.

The surface roots you kept look good. As long as the tree stays healthy, you can further improve the roots the next time you repot.

Thanks, Jonas! Glad to hear I did pretty well for my first time. A few more follow-up questions if you don’t mind:

since I just repotted, should I wait 2 years before bare rooting 50% like you suggested? Or can I essentially repot it immediately?

was I correct that certain roots feed certain branches in junipers?

after I repotted I read that junipers like ‘crappy’ soil, and I noticed that mine has a decent amount of clay-like material. Does that seem right? If so, do you know what material it is so I can purchase in the future?

should I worry that the trunk turns dark and a little wet after watering (as if it’s absorbing up the trunk)? You can see it starting to happen in the photo I posted earlier, but it gets worse than that and has happened since I got the tree.

is there anything else I can do to promote root growth on the other side of the tree (opposite of where all the large ones are coming out)? There is far less root growth on that side.

Sorry for all the questions - trying to learn as much as I can as a rookie!

I’d wait at least a year before repotting again, and likely two, especially if it doesn’t grow a lot in the next year.

To some degree, yes, certain roots feed certain branches

Junipers also like good soil (am not sure what likes “bad” soil as bad in my mind is whatever something doesn’t grow well in)

the trunk darkening when wet sounds natural to me

good soil and good watering is the best way to promote root growth. To balance roots, heavier roots are often shortened to let the smaller roots catch up. Grafting roots can also help. Fortunately, roots aren’t as important on junipers as they are on other varieties.

The main thing at this point is to watch the watering carefully. Keeping the too wet - or too dry - will weaken the tree. Checking the soil between waterings and only watering when the soil is mostly dry 1/4"-1/2" down (in an area where there are roots) is a good starting point.